Loose's ground when key is on

[Fish]

Disconnect the kill wire to the ignition while you figure things out,

voltage will damage an ignition coil.

 

[mechanic mark]

Run a new ground wire from frame to hour meter.

 

[Hammermechanicman]

A couple things.
The hour meter connects to A1 of the ignition stitch. You should only have power to hourmeter when key is on.
Most husqvarna mowers have a 12ga black wire that is a common ground for most of the circuits. That wire corroding the ring connector is a common problem on husqvarna mowers. If you have meter check resistance from the coil kill wire to engine block with the ignition switch in the off position the check from kill wire to batt-. What are the resistance readings?
Pull the connector off the ignition switch and measure resistance from G ground terminal in the connector to engine block and then to batt-. What are the resistance readings?

 

[poppie59]

What do you mean negative charge to the coil? Did the new solenoid match the old one?
Was the keyswitch you put on the correct one? The letters on the back must match, the same number of prongs don't mean that they are the same?